When you're building a one-of, you need something that fits in the sort of package that the 8041/42 used to fit, namely a DIP40 or PLCC44. The reason is simple, namely, that it's going to have to fit on the prototype area of another board, since it's a perpheral controller. That kind of a chip would work REALLY well for some of the small-lot things I whip up from time to time.

If it's going to require a custom PCB, while there are folks who'd probably whip one up for me in a few hours, provided I provide films and drill tool, it would be too much to ask that I then assemble and test the board too. In a couple of hours I can wire up an 8741/42 and use that, if it's capable and called-for.

I'm really considering trying one of the fast Dallas chips, e.g. DS89C4x0 in that way sometime soon, just to see whether it responds to an interrupt fast enough to meet "classic" microcontroller bus timing, e.g. 250 ns access from chip-select. I'm not yet sure what the best way to do this would be, in light of the possibility of using a wait line. Maybe a 9-bit buffer, with a default-active WAIT line fed back to the selecting CPU, disabled with a bit from the DS89C4x0 when it's ready to finish the transaction.

Maybe someone will have a way to do it on an 805x bus, as a memory-mapped peripheral controller.

RE